Consolidation joining of thermoplastic laminate ducts

ABSTRACT

There is provided an apparatus and method for consolidation joining a thermoplastic preform to form a duct. The apparatus includes first and second longitudinally extending support structures. The first support structure at least partially defines a cavity for supporting the preform in a desired configuration of the duct. The second support structure extends in the cavity such that the preform can be supported between the first and second support structures. The second support structures can include an elastomeric device that is configured to adjust radially and urge the interface of the preform against the first support structure. A heater is configured to heat an interface of the preform to above a glass transition temperature. The resulting duct is has a longitudinal consolidation joint and defines a passage.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to apparatuses and methods for formingducts and, more specifically, thermoplastic ducts formed byconsolidation joining.

2) Description of Related Art

Ducts provide transport passageways for a wide variety of applications.For example, tubular ducts are widely used for air flow in aircraftenvironmental control systems. Similarly, ducts provide passageways fortransporting gases for heating and ventilation in other vehicles and inbuildings. Water distribution systems, hydraulic systems, and otherfluid networks also often use ducts for fluid transport. In addition,solid materials, for example, in particulate form can be deliveredthrough ducts. Ducts for the foregoing and other applications can beformed of metals, plastics, ceramics, composites, and other materials.

One conventional aircraft environmental control system utilizes anetwork of ducts to provide air for heating, cooling, ventilation,filtering, humidity control, and/or pressure control of the cabin. Inthis conventional system, the ducts are formed of a composite materialthat includes a thermoset matrix that impregnates, and is reinforced by,a reinforcing material such as Kevlar®, registered trademark of E. I. duPont de Nemours and Company. The thermoset matrix is typically formed ofan epoxy or polyester resin, which hardens when it is subjected to heatand pressure. Ducts formed of this composite material are generallystrong and lightweight, as required in many aircraft applications.However, the manufacturing process can be complicated, lengthy, andexpensive, especially for specially shaped ducts such as curved ductsand ducts that include a spud or attached fitting, a bead, a bell orflared portion, a conical section, or another contour. For example,curved ducts are conventionally formed around a disposable plastermandrel. The plaster mandrel is formed in a specially shaped rotatabletool that acts as a mold to form the plaster mandrel according to thedesired shape of the duct. First, a cavity of the tool is partiallyfilled with uncured plaster, and the tool is rotated so that the plastercoats an inner surface of the tool cavity. When the plaster is partiallycured to form the mandrel, the tool is stopped and opened so that theplaster mandrel can be removed and placed in an oven for subsequentcuring. The mandrel is then treated with a sealant, cured again, andtreated with a release agent. Plies of fabric, such as Kevlar®,preimpregnated with the thermoset material are cut and draped over themandrel, often by hand, and a heat gun is used to mold the plies to theshape of mandrel. The mandrel is placed in a vacuum bag, which is fittedwith one or more valves, and air is evacuated from the bag through thevalves so that the bag urges the plies against the mandrel andconsolidates the plies while heat is applied to cure the plies and formthe duct. When the plies are cured, the vacuum bag is removed and theplaster mandrel is broken and removed from the duct. The duct is cleanedand trimmed to the desired dimensional characteristics. One or more jigsthat correspond to the desired shape of the duct are often used fortrimming the duct and for accurately locating additional features on theduct such as holes, spuds, brackets, and the like. Further processing issometimes necessary for adding a bead or bell so that one or both endsof the duct can be secured and sealed to another duct. Typically, a beadis formed by adding additional material, thus adding weight to the duct.Insulation can also be added to the inside and/or outside of the duct.

The manufacturing process for such reinforced thermoset ducts iscomplicated, time consuming, and expensive. The rotatable tool used tomold the plaster mandrel is specially sized and shaped for creating aduct of specific dimensions, so numerous such tools must be produced andmaintained for manufacturing different ducts. The plaster mandrel isformed and destroyed during the manufacture of one duct, requiring timefor curing and resulting in plaster that typically must be removed ordestroyed as waste. Additionally, the preimpregnated plies change shapewhile being cured and consolidated and therefore typically must betrimmed after curing to achieve the desired dimensions. The jigsrequired for trimming and for locating the proper positions for featuressuch as holes and spuds are also typically used for only a duct ofparticular dimensions, so numerous jigs are required if different ductsare to be formed. Like the rotatable tools used for forming themandrels, the jigs require time and expense for manufacture, storage,and maintenance.

Additionally, ducts formed of common thermoset epoxies do not performwell in certain flammability, smoke, and toxicity tests, and the use ofsuch materials can be unacceptable if performance requirements arestrict. For example, changes in environmental laws or proposed changesto performance requirements mandated by the Federal AviationAdministration would prevent the use of ducts formed from some thermosetcomposites in certain aircraft environmental control systemapplications.

One proposed alternative to thermoset composite materials isthermoplastic composites. Thermoplastic composites become plasticallydeformable when heated above a glass transition temperature. Instead oflaying plies of uncured composite material on a mandrel, a sheet ofthermoplastic composite material can be manufactured and then heated andformed to a desired shape. Thus, a part can be formed from athermoplastic composite without using a disposable plaster mandrel and aspecial tool for forming the mandrel.

The formation of certain shapes of parts, such as ducts, fromthermoplastic composite materials requires the formation of joints.Methods for joining members formed from thermoplastic composites areknown in the art, but none of the known methods are ideal. Generally,each method of joining thermoplastic composite members includes heatingthe members to a temperature above the glass transition temperature andholding the members together. One method of providing heat to themembers is by generating friction between the members, for example, byreciprocating, ultrasonically vibrating, or friction stirring themembers. Undesirably, composites that contain fiber reinforcements,especially long or continuous fibers, can be damaged by these frictionalheating methods. Locating tools and backing members for supporting themembers are often required, and large members can be difficult toreciprocate. Additionally, ultrasonic methods typically require surfacepreparations, and friction stirring is typically slow.

Alternatively, heat can be applied by conduction or convection, forexample, by hot plate joining, hot gas joining, extrusion joining, orresistance joining. In hot plate joining, a plate is heated and insertedat an interface of the members. The plate is then removed and themembers are pressed together. Hot plate joining generally requiressimple tooling but is time consuming and is not practical for use withcomplex shapes. Further, the hot plate can introduce contamination intothe interface of the members or oxidize the composite materials, therebyweakening the joint. Hot gas joining is similar to conventional metalwelding. An operator inserts a filler rod, typically formed of thecomposite material, into the interface and directs a stream of hot gasto heat the members and the rod. The gas plasticizes the members and therod, which provides additional material into the interface. Similarly,extrusion joining is performed by heating the filler rod in an extruderand extruding the heated rod material into the interface while using thehot gas to heat the members. Hot gas and extrusion joining are typicallyslow, and the quality of the resulting joint can vary significantlydepending on the skill of the operator. In resistance joining, anelectrically conductive heating element is inserted into the interface.The members are pressed together, and the heating element iselectrically energized, causing resistive heating therein, which heatsthe members. The heating element, which remains in the joint, increasesthe cost of the joining method and affects the characteristics of thejoint, for example, making the joint stiffer than the other portions ofthe members. Typically, the heating element has a different coefficientof thermal expansion than the thermoplastic material, resulting instresses in the joint when heated or cooled.

Finally, heat can be provided to the interface by electromagnetism, forexample, by electromagnetic joining, microwave joining, laser joining,and infrared joining. Electromagnetic joining is accomplished bydispersing a metallic powder in a bonding material in the interface ofthe members to be joined. A magnet is moved proximate to the interface,thereby generating heat in the powder. The powder adds to the cost ofthe joint, and the method is generally limited to joining members oflimited thickness. Where a first member has a low absorption and asecond member has a high absorption, laser joining can be used bydirecting a laser beam through the first member so that it is absorbedat the interface by the second member. Laser joining is generally notapplicable where the members do not have dissimilar absorptions. Inmicrowave joining, a material susceptible to microwaves is placed in theinterface, and the interface is irradiated with microwaves. The methodis typically used only if the members are not significantly absorptiveof microwaves. Infrared joining, i.e., using an infrared lamp to heatthe interface and then pressing the members together, requires acomplicated set up and can be time consuming, depending on theabsorption characteristics of the members.

Thus, there exists a need for an improved apparatus and method offorming ducts that is effective and cost efficient. Preferably, themethod should not require that individual plies be laid on a plastermandrel. The method should be compatible with plastic and compositematerials that provide high strength-to-weight ratios and meet strictflammability, smoke, and toxicity standards. Further, the method shouldprovide a method of forming strong joints and should be adaptable forautomated operation to achieve consistent results.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method for formingthermoplastic ducts with consolidation joints. The ducts can be formedof preforms, which can be thermoplastic laminate sheets preformed to abent configuration. The thermoplastic material is lightweight, strong,and performs well in flammability, smoke, and toxicity tests. Further,the disposable plaster mandrels for supporting plies are not required,nor are duct-specific rotatable tools for forming such mandrels.Additionally, consolidation joints achieved by the apparatus and methodcan be strong, and the method is adaptable for automated operation.

In one embodiment, the present invention provides an apparatus forconsolidation joining a thermoplastic preform to form a duct having alongitudinal consolidation joint and defining a passage. The apparatusincludes first and second longitudinally extending support structures.The first support structure at least partially defines a cavity capableof supporting the preform in a preformed configuration that correspondsto a desired configuration of the duct. The second support structureextends in the cavity defined by the first support structure such thatthe preform can be supported between the first and second supportstructures. At least one of the support structures can be adjustedradially so as to urge the preform against the other support structure.The apparatus also includes a heater assembly that is configured to heatan interface of the preform to above a glass transition temperature. Atleast one of the support structures or the heater assembly can beelastomeric so as to conform to the interface of the preform and provideeven pressure along the seam.

According to one aspect of the invention, the second support structureincludes a rigid elongate member with an outer surface that correspondsto the desired configuration of the duct. The first support structure isadapted to adjust toward the second support structure from a firstposition to a second position and thereby configure the preform to thedesired configuration of the duct. The first support structure caninclude a plurality of rods that extend longitudinally and areadjustable radially relative to the second support structure so that therods can be adjusted radially inward toward the elongate member toconfigure the preform to the desired configuration. Actuators can beincluded for adjusting the rods.

According to another aspect, the second support structure includes aninflatable bladder connected to the rigid member. The bladder isconfigured to receive a fluid for inflating and expanding radiallyoutward toward the first support structure to urge the preform againstthe first support structure. An anvil corresponding to the desired shapeof the duct can be positioned to oppose the bladder so that the bladdercan urge the preform against the anvil. The heater assembly can includea heater positioned outside the cavity and in thermal communication withan outer surface of the preform, and/or a flexible heater disposed onthe bladder so that the flexible heater can be urged against aninterface of the preform. At least one longitudinally extending coolingmanifold can be positioned proximate to the preform to receive a coolingfluid for cooling the preform.

According to yet another aspect of the present invention, the secondsupport structure includes the elastomeric device, which is configuredto receive a fluid for inflation. The elastomeric device can be inflatedto fill the cavity and exert a radially outward pressure, for example,of at least about 20 psi on the preform. The first support structure caninclude a hollow tube that extends from a first end to a second end anddefines a cylindrical cavity therein. The tube can define a slit thatextends longitudinally between the ends so that the tube can be adjustedbetween a closed position and an open position, and the diameter of thetube is reduced by closing the tube.

The present invention also provides a method of forming a thermoplasticlaminate duct. The thermoplastic laminate preform can initially beformed by impregnating a reinforcement material such as an aramid,carbon, or glass with a thermoplastic such as polyetherimide orpolyphenol sulfide. The method then includes configuring a thermoplasticlaminate preform generally to a desired shape of the duct that extendslongitudinally and defines a passage. The preform can be configured byactuating a support structure, such as a plurality of longitudinallyextending rods, radially inward to bend the preform about a longitudinalaxis, for example, about a longitudinal member. A first longitudinaledge of the preform at least partially overlaps a second longitudinaledge of the preform to define an interface between first and secondsurfaces of the preform. The first and second surfaces of the interfaceare urged together, for example, by filling a bladder with fluid. Thebladder can fill a cavity of an outer support structure and urge thepreform radially against the outer support structure. Alternatively, thebladder can be positioned between a beam extending longitudinallythrough the passage of the preform and the preform so that the bladderurges the preform radially outward and against an outer supportstructure. The interface is heated while urged together so that theinterface is consolidated to form a joint. For example, at least oneresistive heater can be electrically energized to generate thermalenergy, which is conducted as heat to the preform. Heaters can bepositioned in the passage of the preform and/or outside the preform.Preferably, the interface is heated to above a glass transitiontemperature of the preform. Subsequent to the heating, the joint can becooled to a temperature below the glass transition temperature of thepreform while continuing to urge the first and second surfaces of theinterface together. For example, fluid can be circulated through amanifold in thermal communication with the interface of the preform.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is a perspective view of a partially assembled consolidationjoiner apparatus according to one embodiment of the present invention;

FIG. 2 is a perspective view of a bladder for use with the consolidationjoiner apparatus of FIG. 1;

FIG. 3 is a perspective view of a duct formed with a consolidationjoiner apparatus according to one embodiment of the present invention;

FIG. 4 is a perspective view of a thermoplastic preform for forming theduct of FIG. 3;

FIG. 5 is a perspective view of a bent, or preformed, preform formedfrom the preform of FIG. 4;

FIG. 6 is a perspective view of the consolidation joiner apparatus ofFIG. 1 with the preform and bladder inserted;

FIG. 7 is a perspective view of the consolidation joiner apparatus ofFIG. 6 with the end plates installed and the pressure source and powersupply connected;

FIG. 8 is a perspective view of the consolidation joiner apparatus ofFIG. 7 with the insulation installed;

FIG. 9 is an elevation view of a consolidation joiner apparatusaccording to another embodiment of the present invention;

FIG. 10 is an elevation view of the consolidation joiner apparatus ofFIG. 9 with the preform installed; and

FIG. 11 is a section view of the consolidation joiner apparatus of FIG.10 as seen along line 11—11 of FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring now to FIG. 1, there is shown a consolidation joiner 10 forforming consolidation joints in thermoplastic members according to oneembodiment of the present invention. The consolidation joiner 10includes an outer support structure comprised of a tube or elongatecylinder 12 that extends longitudinally from a first end 14 to a secondend 16 and defines a continuous cavity 11 therethrough. In thisembodiment, the elongate cylinder 12 defines a cylindrical cavity 11that is uniform along the length of the cylinder 12, but in otherembodiments, other cross-sectional shapes can also be defined by thecavity 11, and the cross-sectional size or shape may be non-uniformalong the length of the cylinder 12. For example, the consolidationjoiner 10 can define an elliptical or rectangular cavity, which cantaper in the longitudinal direction. A slit 18 extends longitudinallybetween the ends 14, 16 of the cylinder 12. Flanges 20 parallel to theslit 18 are fitted with bolts 22 or other fasteners so that the slit 18can be opened or closed and the diameter of the cylinder 12 can beadjusted accordingly. Preferably, the cylinder 12 is biased to an openconfiguration so that the slit 18 is open unless the bolts 22 aretightened to close the slit 18. End plates 28 correspond to the ends 14,16 of the cylinder 12, and bolt holes 24 at the ends 14, 16 of thecylinder correspond to bolt holes 32 of the end plates 28 so that theend plates 28 can be positioned to close the ends 14, 16 and bolts (notshown) can be inserted and tightened to secure the end plates 28thereon. The consolidation joiner 12 is supported by base supports 26,though other conventional support structures can also be provided. Thecylinder 12 and end plates 28 can be formed of a variety of materialsincluding, but not limited to, steel, aluminum, titanium, composites,and alloys thereof. Additionally, there can be disposed on the workingsurfaces of the cylinder 12 and end plates 28 a low friction layer orrelease layer, e.g., Teflon®, registered trademark of E. I. du Pont deNemours and Company. The release layer can be a durable layer ofmaterial or a release agent that is wiped or sprayed onto the workingsurfaces before each consolidation joining process.

The consolidation joiner 10 also provides an inflatable bladder 40, asshown in FIG. 2, which can be inserted in the cavity 11 of the cylinder12 prior to installing the end plates 28. The bladder 40 provides atleast one valve 44, which can be mounted on a stem 42. According to theembodiment shown in FIG. 2, the bladder 40 includes two stems 42extending longitudinally therefrom and a valve 44 at the end of eachstem 42. The valves 44 are configured to receive fluid, i.e., a gas orliquid, for inflating the bladder 40. Preferably, the bladder 40 isformed of an elastomeric material such as silicone, rubber, or neoprene,which allows the bladder 40 to expand during inflation. A low frictionmaterial or film, such as Teflon®, can also be disposed on the bladder40.

The consolidation joiner 10 can be used to form a seam or joint in athermoplastic material. For example, the consolidation joiner 10 canform a cylindrical thermoplastic duct 70 as shown in FIG. 3. The duct 70extends longitudinally from a first end 72 to a second end 74 anddefines a passage 76. A seam or joint 78 extends longitudinally betweenthe ends 72, 74 of the duct 70. The duct 70 can include a variety ofconnection features such as a spud hole 80 and detail holes 82. The spudhole 80 can be located on the duct 70 to coincide with a desiredlocation for a spud (not shown), or fitting, which can be used tofluidly connect the passage 76 of the duct 70 to another duct or device.The details hole 82 can be configured to receive bolts, screws, rivets,clips, or other fasteners for connecting a detail device such as abracket (not shown) to the duct 70.

Preferably, the duct 70 is formed of a composite laminate that includesa thermoplastic matrix and a reinforcing material. Thermoplasticmaterials are characterized by a transition to a plastic state whenheated above a glass transition temperature. For example, the duct 70can be formed of polyetherimide (PEI) or polyphenol sulfide (PPS), bothof which can be thermoplastic. Thermoplastic PEI is available under thetrade name Ultem®, a registered trademark of General Electric Company.According to one embodiment of the present invention, each duct 70 isformed of a composite material that includes a matrix of thermoplasticPEI that is reinforced with a reinforcing material such as carbon,glass, or an aramid fabric such as Kevlar®, or fibers of such amaterial. Alternatively, the duct 70 can be formed of otherthermoplastic materials, which can be reinforced by other reinforcingmaterials, or can include no reinforcing materials.

The duct 70 can be used in numerous applications including, but notlimited to, environmental control systems of aerospace vehicles, inwhich air is delivered through the passage 76 of the duct 70 to provideheating, cooling, ventilation, and/or pressurization of an aircraftcabin. The ends 72, 74 of the duct 70 can be connected to other ducts orother devices such as ventilators, compressors, filters, and the like.Multiple ducts 70 can be connected so that a longitudinal axis of eachduct 70 is configured at an angle relative to the longitudinal axis ofthe adjoining duct(s) 70. Thus, the ducts 70 can be connected to form anintricate duct system (not shown) that includes numerous angled orcurved ducts for accommodating the devices connected by the duct systemand for meeting layout restrictions as required, for example, on anaircraft where space is limited.

There is illustrated in FIG. 4 a preform 90 for forming the duct 70. Thepreform 90 comprises a flat sheet of thermoplastic laminate and definesthe first and second ends 72, 74, first and second longitudinal edges92, 94, and the connection features 80, 82. Preferably, the preform 90defines a geometric pattern that corresponds to a desired shape orconfiguration of the duct 70. The geometric pattern of the preform 90 isdetermined by projecting the desired shape of the duct 70 onto the flatlaminate sheet shown in FIG. 4. Methods and apparatuses for formingpreforms and for determining geometric patterns that correspond to ductsare provided in U.S. application Ser. No. [. . . ], titled“Thermoplastic Laminate Duct,” filed concurrently herewith, the entiretyof which is incorporated herein by reference.

Preferably, the preform 90 is also bent, or “preformed,” to at leastgenerally correspond to the desired spatial configuration of the duct70. For example, there is shown in FIG. 5 a preformed preform 90 that isbent or rolled so that the first and second longitudinal edges 92, 94are brought into proximity and the preform 90 defines the passage 76 andgenerally forms the cylindrical shape of the duct 70 of FIG. 3. Thepreform 90 illustrated in FIG. 5 is configured in the illustratedpreformed shape such that the preform 90 tends to retain that shape,i.e., the preform 90 can be configured from the bent or preformed shapeto the precise desired shape of the duct 70 without inducing significantstresses in the preform 90. The preform 90 can be bent in a circularcross section, as illustrated, or in another shape such as a square,rectangle, triangle, ellipse, and the like. One of the first or secondlongitudinal edges 92, 94 overlays a portion of the other edge 92, 94 toform an interface 96 therebetween. Methods of configuring preforms to abent, or preformed, configuration are provided in U.S. application Ser.No. [. . . ], titled “Preforming Thermoplastic Ducts,” filedconcurrently herewith, the entirety of which is incorporated byreference.

The preform 90 can be inserted into the elongate cylinder 12 of theconsolidation joiner 10 prior to installing the end plates 28, as shownin FIG. 6. Preferably, the preform 90 defines a cross section that islarger than that of the duct 70, i.e., the preform must be further bentfrom the preformed shape in order to be configured to the desired shapeof the duct 70. In one embodiment, the cylinder 12 is configured toexpand to a size larger than the preform 90 by adjusting the bolts 22 toopen the slit 18. The slit 18 preferably provides enough adjustment tothe cylinder 12 so that closing the slit 18 bends the preform 90 to across sectional size that is smaller than the unrestrained size of thepreform 90. In one embodiment, in which the preform 90 is less thanabout 0.020 inches larger than the desired cross sectional size of theduct 70, the slit 18 can be adjusted to provide at least a 0.020 inchchange in the diameter of the cavity 11 of the cylinder 12. Thus, whenthe cylinder 12 is closed, the preform 90 is slightly bent and thespring force of the preform 90 tends to hold the preform 90 in itsposition in the cylinder 12. Alternatively, if the cylinder 12 does notopen larger than the preform 90, or if no slit 18 is provided in thecylinder 12, the preform 90 is bent further to a size smaller than thecylinder 12 by a manual or automated method and inserted into thecylinder 12.

After the preform 90 is inserted into the cavity 11 of the cylinder 12and the bolts 22 are tightened to close the slit 18, the consolidationjoiner 10 can be assembled. The cylinder 12 is configured to receive thebladder 40 such that the bladder 40 is positioned within the preform 90as shown in FIG. 6. Preferably, the bladder 40 is about as long as thecylinder 12 so that the cylinder 12 can be filled by the bladder 40. Thebladder 40 can be deflated by releasing fluid from at least one of thevalves 44 to facilitate the insertion of the bladder 40 into thecylinder 12, and the bladder 40 can then be inserted longitudinally intothe cylinder 12 from either end 14, 16 so that the stems 42 extend fromthe cylinder 12. As shown in FIG. 7, the end plates 28 are positioned atthe ends 14, 16 of the cylinder 12 and secured with bolts that extendthrough holes 24 in the cylinder 12 and into corresponding holes 32 inthe end plates 28. The stems 42 extend through the stem apertures 30defined by the end plates 28, and the valves 44 are configured to befluidly connected to a pressure source 50 via pressure hoses 52.Although two valves 44 are shown in FIG. 7, both of which are connectedto the pressure source 50, the consolidation joiner 10 can include anynumber of valves 44, some or all of which can be connected to thepressure source 50 for inflation. The pressure source 50 can comprise acompressor, pump, pressurized fluid vessel, or other devices forsupplying pressurized fluid to the bladder 40. In one advantageousembodiment, the pressure source 50 provides air to the bladder 40, butthe pressure source 50 can also provide other gases, such as nitrogen,or liquids such as water or oil.

The consolidation joiner 10 also includes at least one heater 56, whichcan be permanently attached to the cylinder 12 or removable from thecylinder 12 and/or adjustable on the cylinder 12, for example, by tapingor bolting the heater 56 to the cylinder 12. The heater 56 is a bar orstrip heater, but other types of heaters can be used such as heatingblankets and other electrical resistance heaters, gas heaters, and otherheaters as are known in the art. The heater 56 is advantageouslyconfigured proximate to the interface 96 of the preform 90 so that theheater 56 can be used to heat at least the interface 96 of the preform90 in order to join the edges 92, 94 of the preform 90 and form thelongitudinal seam 78 therealong. The heater 56 is connected to a powersupply 58, which provides electrical energy to the heater 56 forheating. In FIGS. 6–8, the preform 90 is configured in the cylinder 12so that the longitudinal edges 92, 94, and hence the interface 96, ispositioned at the top of the cylinder 12, but the preform 90 canalternatively be configured so that the interface 96 is positioned atany other angular position. Preferably, the heater 56 is configuredoutside the cylinder 12 to directly oppose the position of the interface96, e.g., at the top of the cylinder 12 in FIG. 7. Insulation 60 canalso be provided around part of all of the cylinder 12 and heater 56 toincrease the thermal energy retained by the consolidation joiner 10during processing. The insulation 60 can comprise one or more panels orblankets, which can be taped or bolted in place as shown in FIG. 8.

In FIGS. 1–8, the consolidation joiner 10 includes an outer supportstructure comprising the elongate cylinder 12, each of which has a fixeddiameter defined by the closed position and are typically used forconsolidation joining preforms 90 of a particular size that correspondsto the cavity 11 of the cylinder 12. However, in other embodiments, thepresent invention provides an adjustable outer structure that can beused to support preforms 90 of different diameters. For example, thereis shown in FIGS. 9–11 a consolidation joiner 110 that includes an outersupport structure comprising ring supports 112, each arranged about acommon longitudinal axis. The ring supports 112 support actuators 114,which are configured to support a plurality of parallel rods 116, six inthe illustrated embodiment, and adjust the rods 116 radially inward andoutward. As shown in FIG. 11, the rods 116 can be adjusted radially todefine an adjustable cavity 111 therein and, thus, support preforms 90of different diameters and/or shapes.

The outer support structure of the consolidation joiner 110 alsoincludes an anvil 130, which is supported by an anvil support structure132. Preferably, the anvil 130 is shaped according to the desired shapeof the duct 70. For example, the anvil 130 may have an arcuate shape ofa predefined radius. The anvil 130 can be removable from the supportstructure 132 so that anvils 130 of different sizes and shapes can beinstalled according to the duct 70 that is being processed. Further, theanvil support structure 132 can be adjustable to accommodate differentanvils 130. For example, the anvil support structure 132 can includemounting spacers 134 that can be replaced with mounting spacers 134 ofdifferent sizes according to the width of the anvil 130 that issupported by the support structure 132. The support structure 132 alsosupports a heater 136, which can be a bar heater as illustrated in FIG.11, or various other types of heaters as are known in the art.Preferably, the heater 136 is located proximate to the anvil 130 so thatheat from the heater 136 can be conducted by the anvil 130 to thepreform 90 during processing. A fluid manifold 138 is also supported bythe support structure 132 and located near the anvil 130. The fluidmanifold 138 is configured to receive a fluid, for example, from a fluidsource to cool the preform 90. At least one edge stop 140 is configuredto extend from the support structure 132 toward the preform 90. Forexample, as illustrated in FIG. 11, each edge stop 140 is biased by aspring 142 to extend through the anvil 130. The edge stops 140 can belocated at various positions along the length of the support structure132 and can be integral to the anvil 130.

An inner beam 150, which extends from a first end 170 to a second end172, is positioned in the cavity 111 defined by the rods 116 such thatthe preform 90 can be positioned around the inner beam 150. Although theends 170, 172 of the inner beam 150 are connected to the anvil supportstructure 132, at least one of the ends 170, 172 of the inner beam 150can be disconnected from the anvil support structure 132 to facilitatethe insertion of the preform 90 into the cavity 111 of the consolidationjoiner 110. For example, a latch 166 can be adjusted between an openposition and a closed position. With the latch 166 in the open position,shown in FIG. 9, the preform 90 can be inserted longitudinally into theconsolidation joiner 110 such that the preform 90 is disposed around theinner beam 150 with the interface 96 positioned between the inner beam150 and the anvil 130. The edge stops 140 can be used to position theinterface 96 between the inner beam 150 and the anvil 130. For example,the preform 90 can be inserted into the cavity to enclose the inner beam150 and then rotated until one of the longitudinal edges 92, 94 of thepreform 90 contacts the edge stops 140, preventing further rotation. Ifthe preform 90 is positioned so that the first edge 92 is positionedoutside the preform 90 as shown in FIG. 11, the preform is rotated in aclockwise direction until the first edge 92 is rotated over the anvil130 and contacts the edge stops 140. When the preform 90 is properlypositioned in the cavity 111, the latch 166 can be moved to the closedposition, shown in FIG. 10, securing the inner beam 150 in positionrelative to the anvil 130.

As shown in FIG. 11, the inner beam 150 includes a rigid member 151 andan inflatable seal 152, or bladder, that is connected to the rigidmember by a seal retainer 156 and/or screws (not shown) and locatedopposite the anvil 130. Preferably, the inflatable seal 152 is formed ofan elastomeric material and defines a fluid passage 154 such that theinflatable seal 152 can receive a fluid in the fluid passage 154 and beinflated to urge the preform 90 against the anvil 130. For example, theinflatable seal 152 can be formed of silicone, rubber, neoprene, orother flexible materials. A flexible silicon heater 162 is provided onthe inflatable seal 152 such that the heater 162 is urged toward thepreform 90 when the inflatable seal 152 is inflated. Thus, the heater162 can be used to radiate heat radially outward to heat the interface96 of the preform 90 during consolidation joining. A low-friction film164 disposed on the inflatable seal 152 reduces the tendency of thepreform 90 to stick to the inflatable seal 152 and/or the heater 162.For example, the low-friction film 164 can be formed of Teflon®. Each ofthe flexible silicon heater 162 and the bar heater 136 can compriseother types of heaters as are known in the art. Additionally, in otherembodiments, the consolidation heater 110 can include only one of theheaters 136, 162.

During operation, the consolidation joiners 10, 110 are used toconsolidation join the edges 92, 94 of the preform 90 to form the joint78 in the duct 70 by providing pressure and heat to the interface 96 ofthe preform 90. Pressure is provided to the interface 96 by supportingthe preform 90 in the cavity 11, 111 defined by one of the outer supportstructures, for example, the cylinder 12 of FIG. 1 or the rods 116 andthe anvil 130 of FIG. 11, and filling one of the bladder 40 orinflatable seal 152 to urge the preform 90 radially outward, forexample, with a pressure of about 20 psi. Heat is provided by one ormore of the heaters 56, 136, 162, which are preferably configured toheat the interface of the preform 90 to above a glass transitiontemperature at which the thermoplastic material of the preform 90becomes plastically formable, for example, about 417° F. for a compositeformed of polyetherimide. In other embodiments the consolidationpressure and temperature can be higher, for example, 60 psi and 650° F.or higher.

More particularly, the consolidation joiner 10 of FIG. 1 can be used toconsolidation join the preform 90, as shown in FIG. 4 or 5, to form theduct 70 of FIG. 3. The cylinder 12 of the consolidation joiner 10 isopened by loosening the bolts 22 and separating the flanges 20 to openthe slit 18. The preform 90 is positioned in the cavity 11 of thecylinder 12, as shown in FIG. 6, and thermocouples 62 can be placed inor proximate to the interface 96 of the preform 90 to accurately monitorthe temperature of the interface 96 during processing using a monitor 64that is electrically connected to the thermocouple(s) 62. Thetemperature of the interface 96 can also be estimated without directlymeasuring the preform 90. For example, if the cylinder 12 is longer thanthe preform 90 that is being processed, one or more pieces of scrapmaterial (not shown) made of substantially the same material as thepreform 90 and substantially the same thickness as the preform 90 can beput in the cylinder 12 in a space not occupied by the preform 90, andthe thermocouples 62 can be placed in, on, or under the scrap material.Two or more pieces of scrap material can be overlapped in the cylinder12 so that the thermal variation between the scrap materials accuratelyreplicates the thermal variation in the interface 96. The bladder 40 isdeflated and inserted longitudinally into the cylinder 12 within thepreform 90, so that the stems 42 extend from the cylinder 12. The bolts22 are tightened to close the slit 18 and, hence, the cylinder 12. Theendplates 28 are positioned at the ends 14, 16 of the cylinder 12 sothat the stems extend therethrough, and the bolts are installed tosecure the end plates 28 to the cylinder 12, as shown in FIG. 7. Thepressure source 50 is connected to one or both of the valves 44. Theheater 56 is connected to the cylinder 12, for example, by bolting ortaping, and the heater is connected to the power supply 58. Preferably,the heater 56 is installed to oppose the interface 96 of the preform 90so that heat can be conducted from the heater 56, through the cylinder12, and to the interface 96. The insulation 60 is configured around thecylinder 12, and fasteners such as bolts, clips, tape, or the like areused to secure the insulation 60 in place.

With the consolidation joiner 10 assembled as shown in FIG. 8, thebladder 40 is inflated, for example to a pressure of about 20 psi orhigher, so that the bladder 40 exerts a force radially outward on thepreform 90, urging the preform to conform to the shape of the cylinder12 and urging the edges 92, 94 of the preform together at the interface96. The power supply 58 is energized to provide electrical energy to theheater 56, which generates heat. The heat is conducted from the heater56 to the preform 90 and heats the interface 96, preferably to above theglass transition temperature of the preform 90. In one embodiment, inwhich the preform 90 comprises PEI, the heater 56 heats the interface 96to a temperature of between about 417° F. and 480° F. For example, theinterface can be heated to about 460° F. The monitor 64 is used tomonitor the temperature of the preform 90 (or scrap) so that the desiredtemperature can be achieved at the interface 96, and the desiredtemperature is maintained for a predetermined consolidation interval,for example, about 15 minutes. The force exerted by the bladder 40 urgesthe longitudinal edges 92, 94 together and consolidates the interface 96to form the duct 70 with the joint 78, which is preferably substantiallysmooth on both the interior and exterior of the duct 70. After theconsolidation interval has passed, the heater 56 is turned off and theduct 70 begins to cool. Preferably, the duct 70 is cooled to atemperature below the glass transition temperature before the bladder 40is deflated, the consolidation joiner 10 is disassembled, and the duct70 is removed therefrom.

According to another embodiment, the consolidation joiner 110 of FIG. 9can also be used to form the duct 70 of FIG. 3 from one of the preforms90, as shown in FIG. 4 or 5. The axial actuators 114 are retracted toretract the rods 116 radially outward, the latch 166 is opened, and theinflatable seal 152 is deflated. The preform 90 is longitudinallyinstalled in the consolidation joiner 110 around the inner beam 150 sothat the interface 96 is positioned between the inflatable seal 152 andthe anvil 130. As described above, thermocouples (not shown) can beplaced in or proximate to the interface 96 of the preform 90 to monitorthe temperature of the interface 96 during processing using a monitor(not shown), or the thermocouples can be used to measure a piece ofscrap (not shown). The latch 166 is closed to secure the first end 170of the inner beam 150 to the anvil 130. The pressure source 160 isconnected to the inflatable seal, the power supply is electricallyconnected to the heaters 136, 162, and the fluid source 139 is connectedto the fluid manifold 138.

With the consolidation joiner 110 assembled as shown in FIG. 10, theactuators 114 are actuated to extend the rods 116 radially inward sothat the rods 116 contact the preform 90 and support the preform 90 asshown in FIG. 11. The inflatable seal 152 is inflated with fluid fromthe pressure source 160 so that inflatable seal 152 exerts a forceradially outward on the preform, urging the longitudinal edges 92, 94 ofthe preform 90 together at the interface 96. The power supply 137 isenergized to provide electrical energy to the heaters 136, 162, whichgenerate heat that is conducted from the heaters 136, 162 to the preform90 at the interface 96. Preferably, the heaters 136, 162 heat theinterface 96 to above the glass transition temperature of the preform90, as described above. The force exerted by the inflatable seal 152urges the longitudinal edges 92, 94 of the preform 90 together andconsolidates the interface 96 to form the duct 70 with the joint 78.After the consolidation interval has elapsed, the heaters 136, 162 areturned off and the duct 70 cools. Preferably, the duct 70 is cooled to atemperature below the glass transition temperature before the inflatableseal 152 is deflated, the latch 166 is opened, and the duct 70 isremoved from the consolidation joiner 110.

The consolidation joiners 10, 110 include an elastomeric device such asthe bladder 40 and the inflatable seal 152, which are adjustableradially outward to urge the interface 96 of the preform against theouter support structure of the cylinder 12 or anvil 130, respectively.In each instance, the elastomeric member 40, 152 urges the preform 90against the opposite support structure while the interface 96 is heatedto form a consolidation joint 78 therein.

After the duct 70 has been formed, the duct 70 can be post-formed toprovide additional contours or features, such as bells, beads, and thelike. A discussion regarding the formation of duct features such asbells and beads through post-forming, i.e., after the consolidationjoining of the joint, is provided in U.S. application Ser. No. [. . . ],titled “Post-Forming of Thermoplastic Ducts,” filed concurrentlyherewith, the entirety of which is incorporated by reference. It isappreciated that less than the entire interface 96 of the preform 90 canbe consolidation joined according to the present invention, so that atleast a portion of the interface 96 remains unjoined. Joining of aparticular portion of the interface 96 can be prevented by not providingheat or pressure to that portion or by providing a separation material,such as heat resistant tape, between the edges 92, 94 during theconsolidation joining process. The resulting unjoined portion can beconsolidation joined, for example, as a part of a post-forming process,as discussed in U.S. application Ser. No. [. . . ], titled “Post-Formingof Thermoplastic Ducts.” It is also appreciated that marks can beprovided on the preform 90, for example, to accurately identify thelocation of such post-formed features or to facilitate the manufactureor assembly of the ducts, as provided in U.S. application Ser. No. [. .. ], titled “Thermoplastic Laminate Duct.”

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. As pointed out above, for example, theconsolidation joiner may be configured to form ducts havingnon-cylindrical shapes, such as rectangular, elliptical, or othershapes. Therefore, it is to be understood that the invention is not tobe limited to the specific embodiments disclosed and that modificationsand other embodiments are intended to be included within the scope ofthe appended claims. Although specific terms are employed herein, theyare used in a generic and descriptive sense only and not for purposes oflimitation.

1. An apparatus for consolidation joining a thermoplastic preform toform a duct having a longitudinal consolidation joint and defining apassage, the apparatus comprising: a first support structure extendinglongitudinally and at least partially defining a cavity capable ofsupporting the preform in a preformed configuration that corresponds toa desired configuration of the duct; a second support structureextending longitudinally in the cavity defined by said first supportstructure such that the preform can be supported between said first andsecond support structures, said second support structure comprising arigid elongate member having an outer surface corresponding to thedesired configuration of the duct; and a heater assembly configured toheat an interface of the preform to above a glass transition temperaturewhile the preform is supported between the first and second supportstructures, wherein at least one of said first support structure, saidsecond support structure, and said heater assembly is elastomeric so asto conform to the interface of the preform, and wherein said firstsupport structure is configured to adjust radially from a first positiontoward said second support structure to a second position and therebyurge the preform against the second support structure while the preformis supported in the preformed configuration corresponding to the desiredconfiguration of the duct and thereby configure the preform to thedesired configuration of the duct.
 2. An apparatus for consolidationjoining a thermoplastic preform according to claim 1, wherein said firstsupport structure comprises a plurality of rods extending longitudinallyand adjustable radially relative to said second support structure, suchthat said rods can be adjusted radially inward toward said elongatemember to configure the preform to the desired configuration.
 3. Anapparatus for consolidation joining a thermoplastic preform according toclaim 2, further comprising at least one actuator configured to adjustsaid rods between the first and second positions.
 4. An apparatus forconsolidation joining a thermoplastic preform according to claim 1,wherein said heater assembly comprises an elastomeric support and aheater carried by said elastomeric support such that said heaterassembly can be urged against the interface of the preform to heat theinterface to a temperature above the glass transition temperature of thepreform.
 5. An apparatus for consolidation joining a thermoplasticpreform according to claim 1, wherein said second support structurecomprises an inflatable bladder connected to said rigid member, saidbladder configured to receive a fluid for inflating said bladder andexpanding said bladder radially outward toward said first supportstructure to urge the preform against said first support structure. 6.An apparatus for consolidation joining a thermoplastic preform accordingto claim 5, further comprising an anvil corresponding to the desiredshape of a portion of said duct and positioned in opposing relationshipto said bladder such that said bladder is capable of urging the preformagainst said anvil.
 7. An apparatus for consolidation joining athermoplastic preform according to claim 6, further comprising a secondheater, wherein said heater assembly is positioned outside said cavityand in thermal communication with an outer surface of the preform andsaid second heater is flexible and disposed on said bladder such thatsaid second heater can be urged against an inner surface of the preform.8. An apparatus for consolidation joining a thermoplastic preformaccording to claim 5, further comprising at least one cooling manifoldextending longitudinally and positioned proximate to said preform, saidcooling manifold configured to receive a cooling fluid for cooling thepreform.
 9. An apparatus for consolidation joining a thermoplasticpreform according to claim 1, wherein said second support structurecomprises said elastomeric device which is configured to receive a fluidfor inflating said elastomeric device to fill said cavity and exert aradially outward pressure on the preform.
 10. An apparatus forconsolidation joining a thermoplastic preform according to claim 9,wherein said elastomeric device is capable of being inflated to apressure of at least about 20 psi.
 11. An apparatus for consolidationjoining a thermoplastic preform according to claim 9, wherein said firstsupport structure comprises a hollow tube extending from a first end toa second end and defining said cavity therein, said cavity beingcylindrical.
 12. An apparatus for consolidation joining a thermoplasticpreform according to claim 11, wherein said tube defines a slitextending longitudinally from said first end to said second end suchthat said tube can be adjusted between a closed position in which saidslit is closed and an open position in which said slit is open, adiameter of said tube being greater when said tube is in the openposition than when said tube is in the closed position.
 13. An apparatusfor consolidation joining a thermoplastic preform to form a duct havinga longitudinal consolidation joint and defining a passage, the apparatuscomprising: a plurality of rods extending longitudinally and adjustableradially inward toward a longitudinal axis from a first position to asecond position, such that said rods in the second position at leastpartially define a cavity capable of supporting the preform in apreformed configuration that corresponds to a desired configuration ofthe duct; a rigid elongate member extending longitudinally in the cavitydefined by said rods such that the preform can be supported between saidrods and said elongate member; an inflatable bladder disposed on saidrigid elongate member, said inflatable bladder configured to receive afluid for expanding said inflatable bladder radially outward from saidrigid elongate member; an anvil corresponding to the desired shape of aportion of said duct and positioned in opposing relationship to saidinflatable bladder such that said inflatable bladder is capable ofurging the preform against said anvil; and a heater assembly configuredto heat an interface of the preform to above a glass transitiontemperature.
 14. An apparatus for consolidation joining a thermoplasticpreform according to claim 13, further comprising at least one actuatorconfigured to adjust said rods between the first and second positions.15. An apparatus for consolidation joining a thermoplastic preformaccording to claim 13, wherein said elongate member has an outer surfacecorresponding to the desired configuration of the duct and said rods areadapted to adjust radially relative to said elongate member from thefirst position to the second position and thereby configure the preformto the desired configuration of the duct.
 16. An apparatus forconsolidation joining a thermoplastic preform according to claim 13,wherein said heater assembly comprises a flexible heater disposed onsaid inflatable bladder, said heater capable of being urged against theinterface of the preform to heat the interface to a temperature higherthan the glass transition temperature of the preform.
 17. An apparatusfor consolidation joining a thermoplastic preform according to claim 13,wherein said heater assembly comprises a heater positioned outside saidcavity and in thermal communication with said anvil.
 18. An apparatusfor consolidation joining a thermoplastic preform according to claim 13,further comprising at least one cooling manifold extendinglongitudinally and positioned proximate to said preform, said coolingmanifold configured to receive a cooling fluid for cooling the preform.19. An apparatus for consolidation joining a thermoplastic preform toform a duct having a longitudinal consolidation joint and defining apassage, the apparatus comprising: a tube extending longitudinally froma first end to a second end and defining a cavity capable of supportingthe preform in a preformed configuration that corresponds to a desiredconfiguration of the duct, the tube defining a slit extendinglongitudinally between the first and second ends and defining a single,unitary member extending continuously and circumferentially betweenedges of the slit such that the slit is configured to be opened andclosed to thereby adjust a diameter of the tube, the tube being biasedto an open configuration in which the slit is open; an inflatablebladder extending longitudinally in the cavity defined by said firstsupport structure, said inflatable bladder configured to receive a fluidfor inflating said inflatable bladder to fill said cavity and exert aradially outward pressure on the preform; and a heater assemblyconfigured to heat an interface of the preform to above a glasstransition temperature.
 20. An apparatus for consolidation joining athermoplastic preform according to claim 19, wherein said inflatablebladder is capable of being inflated to a pressure of at least about 20psi.
 21. An apparatus for consolidation joining a thermoplastic preformaccording to claim 19, wherein said cavity of said tube is cylindrical.22. An apparatus for consolidation joining a thermoplastic preformaccording to claim 19, wherein said tube defines a slit extendinglongitudinally from said first end to said second end such that saidtube can be adjusted between a closed position in which said slit isclosed and an open position in which said slit is open, a diameter ofsaid tube being greater when said tube is in the open position than whensaid tube is in the closed position.